Resin composition, molded product thereof and electroconductive sheet

ABSTRACT

An electroconductive sheet comprising a substrate layer of a thermoplastic resin comprising an acrylonitrile-butadiene-styrene copolymer type resin and/or a polystyrene type resin and having laminated on at least one side of the substrate layer, a surface layer of an electroconductive resin composition comprising a polycarbonate type resin and from 5 to 50 wt % of carbon black.

This application is a Divisional Application of application Ser. No.09/926,775 filed on Dec. 18, 2001, now U.S. Pat. No. 6,485,832 IssuedNov. 26, 2002, which is the National Stage of International ApplicationNo. PCT/JP/07516 filed Oct. 26, 2000.

TECHNICAL FIELD

The present invention relates to a resin composition, a molded productemploying it and an electroconductive sheet. Said electroconductivesheet is useful for packaging containers for semiconductors such as ICand electronic parts, particularly useful for carrier tapes.

BACKGROUND ART

For packaging IC, electronic parts using IC or electronic parts,injection-molded trays, vacuum-formed trays, magazines, carrier tapes(referred to also as embossed carrier tapes) etc. have been used. Toprevent breakage of electronic parts such as IC due to staticelectricity, as the packaging containers, ones having anelectroconductive filler dispersed therein have been used. As theelectroconductive filler, carbon black is widely used, with which astable surface resistivity will be obtained constantly at a low cost.

An electroconductive sheet comprising a thermoplastic resin havingcarbon black dispersed therein, has such drawbacks that (1) mechanicalstrength and processability will decrease, and (2) an electronic partwill be stained by falling off of the resin containing carbon black onthe surface of the electroconductive sheet by abrasion of the packagedelectronic part with the electroconductive sheet. JP-A-57-205145,JP-A-62-18261, etc. have been proposed as a method to overcome theproblem (1), and JP-A-9-7624, JP-A-9-76425, etc. have been proposed as amethod to overcome the problem (2). However, electronic parts aregetting more complex, precise and small, and packaging and mounting ofelectronic parts proceed at a higher speed at the present time, andaccordingly, an electroconductive sheet for packaging an electronicpart, which is less likely to cause staining of the electronic part, andwhich has improved mechanical strength, has been desired.

DISCLOSURE OF THE INVENTION

The present invention provides an electroconductive sheet for packagingan electronic part, which substantially reduces staining of theelectronic part due to abrasion of the electroconductive sheet with theelectronic part, and which has adequate mechanical strength to endurepackaging or mounting at a high speed, and a packaging container for anelectronic part. The electroconductive sheet is particularly useful fora carrier tape.

The present invention provides an electroconductive sheet comprising asubstrate layer and having laminated on at least one side of thesubstrate layer, a surface layer of an electroconductive resincomposition comprising a polycarbonate type resin and from 5 to 50 wt %of carbon black based on the polycarbonate type resin. Saidelectroconductive sheet is useful as an electroconductive sheet forpackaging an electronic part, and said electroconductive sheet forpackaging an electronic part is useful as a packaging container for anelectronic part, particularly as a carrier tape.

As a constitution of the electroconductive sheet, a two-layer structureof surface layer/substrate layer, wherein the surface layer comprises anelectroconductive resin composition and is placed on the side which willbe in contact with the electronic part, is preferred. Further, aconstitution of surface layer/substrate layer/surface layer is alsopreferred. Another layer may be provided between the surface layer andthe substrate layer.

The polycarbonate type resin for the electroconductive resin compositionis not particularly limited, and an commercially available product maybe used. For example, an aromatic polycarbonate resin, an aliphaticpolycarbonate resin and an aromatic-aliphatic polycarbonate may bementioned. One obtained by polycondensation of a conventional bisphenolA with phosgene or by polycondensation of bisphenol A with carbonic acidester, which is usually classified into an engineering plastic, may alsobe used. This is composed mainly of bisphenol, and produced by aphosgene method or by ester exchange, and the bisphenol to be used asthe raw material may, for example, be 2,2-bis-(4-hydroxyphenyl)propane(bisphenol A), 2,4-bis-(4-hydroxyphenyl)-methyl-butane or1,1-bis-(4-hydroxyphenyl)-cyclohexane. A homopolycarbonate, acopolycarbonate obtained by copolymerization of a carboxylic acid, or amixture thereof, may also be used.

Carbon black to be incorporated in the electroconductive resincomposition may, for example, be furnace black, channel black oracetylene black, and preferred is one having a large specific surfacearea and whereby a high level of electroconductivity can be obtainedwith a small amount of incorporation to the resin, such as KETJENBLACKor acetylene black.

The amount of carbon black to be incorporated in the electroconductiveresin composition is preferably from 5 to 50 wt % based on thepolycarbonate type resin. If it is less than 5 wt %, no adequate surfaceresistivity will be obtained to prevent breakage of an electronic partdue to static electricity. If it exceeds 50 wt %, the fluidity willdecrease, whereby it may be difficult to laminate the electroconductiveresin composition on the substrate layer, and the mechanical strength ofthe electroconductive sheet to be obtained will also decrease.

The surface resistivity of the electroconductive sheet on the side onwhich the electroconductive resin composition is laminated, ispreferably from 10² to 10¹⁰ Ω. If it is beyond this range, it tends tobe difficult to prevent breakage of an electronic part due to staticelectricity.

Into the electroconductive resin composition, another resin componentsuch as an acrylonitrile-butadiene-styrene copolymer type resin or apolybutylene terephthalate resin may be incorporated as a modifier.

As the modifier, a graft resin of an ethylene-glycidylmethacrylate typecopolymer with an acrylonitrile-styrene type copolymer is suitably used.The electroconductive resin composition in this case comprises apolycarbonate type resin, and from 5 to 50 wt % of carbon black and atmost 40 wt % of a graft resin of an ethylene-glycidylmethacrylate typecopolymer with an acrylonitrile-styrene type copolymer, based on thepolycarbonate type resin. The electroconductive resin composition may bemade of a polycarbonate type resin, carbon black and a graft resinalone, or may be composed mainly of those and contain another componentwithin a range of not impairing the purpose of the present invention.

The graft resin of an ethylene-glycidylmethacrylate type copolymer withan acrylonitrile-styrene type copolymer is a resin obtained by graftingan acrylonitrile-styrene type copolymer to anethylene-glycidylmethacrylate type copolymer, and a resin obtained bygrafting an acrylonitrile-styrene type copolymer having an acrylonitrilecontent of at most 50 wt % to an ethylene-glycidylmethacrylate typecopolymer having a glycidylmethacrylate content of at most 45 wt %, issuitably used, which is commercially available.

The amount of the graft resin to be incorporated is at most 40 wt %,preferably from 1 to 40 wt %, more preferably from 3 to 40 wt %, basedon the polycarbonate type resin. Within the above range, the mechanicalstrength, particularly impact strength, will be improved to endurepackaging and mounting of electronic parts at a high speed. If itexceeds 40 wt %, the elastic modulus will decrease.

When the above resin composition is used for an electroconductive sheetas an electroconductive resin composition, it may be used as a monolayerelectroconductive sheet or a multilayer electroconductive sheet. It maybe used as a molded product by itself.

Into the electroconductive resin composition, an additive such as alubricant, a plasticizer or a processing aid may further be incorporatedas the case requires.

The electroconductive sheet is particularly useful as a carrier tape.For such an application, an electroconductive sheet for a carrier tape,which has a reduced reflection on the surface, has been desired so as toprevent malfunction of an inspection machine due to reflection on thesurface of the electroconductive sheet at the time of image inspectionof e.g. IC. According to the present invention, the layer of anelectroconductive resin composition has a surface roughness Ra of from0.6 μm to 4.0 μm, whereby malfunction of an inspection machine due toreflection on the electroconductive sheet surface can be prevented atthe image inspection of electronic parts such as IC. If the surfaceroughness Ra is less than 0.6 μm, the surface gloss tends to be high,whereby the machine will malfunction due to reflection on theelectroconductive sheet surface at the image inspection, and if itexceeds 4.0 μm, the surface of the electroconductive sheet tends to betoo rough, and the appearance of the sheet tends to be poor, and thesheet is thereby not suitable as an electroconductive sheet for acarrier tape. Here, the surface roughness Ra is a centerline surfaceroughness in accordance with JIS-B-0651.

As a substrate layer, preferred is one comprising anacrylonitrile-butadiene-styrene copolymer type resin and/or apolystyrene type resin, one comprising a polyethylene terephthalate typeresin and a polycarbonate type resin, or one comprising an imidatedcopolymer having an aromatic vinyl monomer residue and an unsaturateddicarboxylic acid imide derivative residue. Another component may beincorporated into the substrate layer within a range of not impairingthe purpose of the present invention.

An electroconductive sheet comprising a substrate layer of athermoplastic resin comprising an acrylonitrile-butadiene-styrenecopolymer type resin and/or a polystyrene type resin and havinglaminated on at least one side of the substrate layer, anelectroconductive resin composition comprising a polycarbonate typeresin and from 5 to 50 wt % of carbon black, is one of preferredconstitutions of the electroconductive sheet.

The acrylonitrile-butadiene-styrene copolymer type resin to be used inthe present invention is one composed mainly of a copolymer consistingessentially of three components of acrylonitrile, butadiene and styrene,and a commercially available product may be used. For example, acopolymer obtained by block or graft polymerization of at least onemonomer selected from an aromatic vinyl monomer and a vinyl cyanidemonomer to a diene type rubber, or a blended product with saidcopolymer, may be mentioned. Said diene type rubber is a polymerobtained by polymerizing butadiene as a component, and examples of whichinclude polybutadiene, polyisoprene, an acrylonitrile-butadienecopolymer and a styrene-butadiene copolymer. The aromatic vinyl monomermay, for example, be styrene, α-methylstyrene or an alkyl-substitutedstyrene. The vinyl cyanide monomer may, for example, be acrylonitrile,methacrylonitrile or a halogen-substituted acrylonitrile. Specificexamples of the copolymer and the blended product with said copolymerinclude an acrylonitrile-butadiene-styrene terpolymer and one obtainedby polymer-alloying a polybutadiene to an acrylonitrile-styrenebipolymer. Further, an acrylonitrile-styrene bipolymer containing norubber component is also included.

The polystyrene type resin is a polymer obtained by polymerizing styreneas a component, and examples of which include one composed mainly of apolystyrene resin for general use or an impact resistant polystyreneresin, or a mixture thereof.

In a case where the substrate layer for the electroconductive sheet ismade of at least one thermoplastic resin selected from the groupconsisting of an acrylonitrile-butadiene-styrene copolymer type resinand a polystyrene type resin, a polycarbonate type resin may further beincorporated in an amount of from 1 to 50 wt % based on thethermoplastic resin. By incorporating a polycarbonate type resin, themechanical strength will further be improved. The amount of thepolycarbonate type resin is preferably at most 50 wt % so as to obtainan electroconductive sheet at a low cost.

In a case where a polyethylene terephthalate type resin and apolycarbonate type resin are used for the substrate layer, theproportion of the polyethylene terephthalate type resin is preferablyfrom 35 to 97 wt %, and the proportion of the polycarbonate type resinis preferably from 3 to 65 wt %, based on the total amount of the twocomponents. In such a case, another component may be incorporatedtherein within a range of not impairing the purpose of the presentinvention.

As the polycarbonate type resin, one used for the electroconductiveresin composition for the surface layer may be used. The resin for thesubstrate layer may be the same as or different from one used for thesurface layer. Preferably, the polyethylene terephthalate type resin isfrom 35 to 97 wt %, and the polycarbonate type resin is from 3 to 65 wt%, and more preferably, the polyethylene terephthalate type resin isfrom 51 to 97 wt %, and the polycarbonate type resin is from 3 to 49 wt%, based on the total amount of the polyethylene terephthalate typeresin and the polycarbonate type resin. The folding strength and thesecondary processability of the electroconductive sheet will decrease ifthe compounding ratio of the polycarbonate type resin is too low or toohigh. The balance of the strength and the secondary processability willbe excellent within the above-mentioned ranges.

The polyethylene terephthalate type resin may be one composed mainly ofethylene glycol and terephthalic acid or a dimethyl ester thereof.Further, one having a part thereof substituted with, diethylene glycol,1,4-tetramethylene glycol, 1,4-cyclohexane dimethanol orheptanemethylene glycol in a case of a glycol component, or e.g.isophthalic acid, 1,5-naphthalene dicarboxylic acid or adipic acid in acase of a dicarboxylic acid component, as a copolymerizable monomer, maybe used. Preferred is a polyethylene terephthalate type resin havingfrom 0.1 to 10 mol % of a 1,4-cyclohexane dimethanol component as aglycol component copolymerized, or a polyethylene terephthalate typeresin having from 1 to 10 mol % of an isophthalic acid component as anacidic component copolymerized, from the viewpoint of moldability.

More preferred is a polyethylene terephthalate type resin comprising aglycol component and from 1 to 10 mol % of a 1,4-cyclohexane dimethanolcomponent copolymerized, since crystallization proceeds slowly, and theimpact strength is high. With a copolymer with a higher molar ratio ofthe 1,4-cyclohexane dimethanol component, the crystallization proceedsextremely slowly, whereby there will be problems such as fusion andblocking in extrusion step, drying step or recycle step, or physicalproperties of a molded product tend to be deteriorated.

Further, one having an intrinsic viscosity [η] (hereinafter referred toas IV value) of from 0.6 to 1.0 dl/g is suitably used, as measured at30° C. when the polyethylene terephthalate type resin is dissolved in amixed solvent of 1,1,4,4-tetrachloroethane with phenol (in a weightratio of 60:40). If it is less than 0.6, the electroconductive sheet orthe molded product tends to have insufficient mechanical strength and islikely to break, and if it exceeds 1.0 dl/g, the melt viscosity tends tobe high, and extrudability tends to be poor, whereby the productivitywill decrease. As the polyethylene terephthalate type resin, acommercially available product may be used.

For the substrate layer, an imidated copolymer having an aromatic vinylmonomer residue and an unsaturated dicarboxylic acid imide derivativeresidue may be used. In such a case, it is preferred that the substratelayer further contains an acrylonitrile-butadiene-styrene copolymer typeresin in addition to the imidated copolymer.

The imidated copolymer is a copolymer having an aromatic vinyl monomerresidue and an unsaturated dicarboxylic acid imide derivative residue,and one further having an unsaturated dicarboxylic anhydride residue mayalso be used. It may further contain a rubber-like polymer. With respectto the amount of each component, the rubber-like polymer is from 0 to 40wt %, the aromatic vinyl monomer residue is from 30 to 70 wt %, theunsaturated dicarboxylic acid imide derivative residue is from 20 to 60wt %, and the unsaturated dicarboxylic anhydride residue is from 0 to 15wt %. Further, a copolymerizable vinyl residue may be used in an amountof from 0 to 40 wt %. As the imidated copolymer, a commerciallyavailable product may be used, such as “Malecca” trade name, sold byDenki Kagaku Kogyo K.K.

The acrylonitrile-butadiene-styrene copolymer type resin to be used insuch a case is not particularly limited, and a commercially availableproduct may be used. Particularly preferred is anacrylonitrile-butadiene-styrene copolymer type resin comprising from 5to 93 wt % of a graft copolymer obtained by copolymerizing from 5 to 80parts by weight of a rubber-like polymer with from 20 to 95 parts byweight of a monomer mixture comprising from 60 to 90 wt % of an aromaticvinyl monomer, from 10 to 40 wt % of a vinyl cyanide monomer and from 0to 40 wt % of a vinyl monomer copolymerizable with the above monomers,and a resin composition comprising from 0 to 80 wt % of a vinylcopolymer comprising from 60 to 90 wt % of an aromatic vinyl monomerresidue, from 10 to 40 wt % of a vinyl cyanide monomer residue and from0 to 40 wt % of a vinyl monomer residue copolymerizable these with.

In a case of using an acrylonitrile-butadiene-styrene copolymer typeresin together, the imidated copolymer may be used in an amount of from5 to 93 wt % based on the total amount of the imidated copolymer and theacrylonitrile-butadiene-styrene copolymer type resin. If it is beyondthis range, heat deterioration is likely to result during processing, orno adequate impact strength tends to be obtained.

Carbon black may be incorporated into the substrate layer of anycomposition, in a small amount so as not to impair the fluidity. Byincorporating carbon black, the mechanical strength will furtherimprove, and at the same time, such a problem can be overcome that thethickness of the electroconductive sheet tends to be thin when theelectroconductive sheet is formed into a packaging container, wherebye.g. the corner portion of the packaging container may be transparent.

Carbon black to be incorporated in the substrate layer is notparticularly limited, so long as it can be uniformly dispersed in thesubstrate resin. The amount of carbon black incorporated in theelectroconductive substrate layer, may be within a range of notimpairing the fluidity as mentioned above, and it is preferably from 0.1to 10 wt % based on the thermoplastic resin.

Into the substrate layer of any composition, another known thermoplasticresin component such as a polyethylene resin or a polypropylene resin,an olefin type resin such as a copolymer of ethylene or propylene (suchas an ethylene-ethylacrylate resin, an ethylene-vinyl acetate copolymerresin or an ethylene-α-olefin copolymer resin), or a polyester typeresin such as a polyethylene terephthalate resin or a polybutyleneterephthalate resin, may be incorporated as a modifier. Further, anadditive such as a lubricant, a plasticizer or a processing aid may beincorporated as the case requires. Further, for the substrate layer, theedge or a missed roll of the electroconductive sheet to be generatedduring production of the electroconductive sheet, or a pulverizedproduct of the molded product, may be recycled in an amount of from 5 to50 wt %.

To prepare the electroconductive sheet of the present invention, firstlya part or whole of the starting materials for the electroconductiveresin composition is kneaded and pelletized by means of a conventionalmethod employing e.g. an extruder, and the obtained electroconductiveresin composition is sheeted together with a thermoplastic resincomposition to be an electroconductive substrate sheet by a conventionalmethod employing e.g. an extruder.

With respect to kneading of the electroconductive resin composition,starting materials may be kneaded all at once or may be stepwiselykneaded in such a manner that, for example, carbon black and a half ofthe polycarbonate type resin are kneaded, and then the rest of thematerials are added to the kneaded product, followed by kneading, and itis also possible to add the rest of the materials at the time ofsheeting.

The electroconductive sheet can be prepared by a known method employinge.g. an extruder or a calendering machine. As a method for laminatingthe electroconductive resin composition on the substrate layer, therespective layers may be firstly formed into sheets or films by aseparate extruder and then stepwisely laminated by e.g. athermolaminating method, a dry laminating method or an extrusionlaminating method. Otherwise, the electroconductive resin compositionmay be laminated on the preliminarily formed electroconductive substratesheet, by e.g. extrusion coating. In order to prepare theelectroconductive sheet at a lower cost, it is preferred to obtain alaminated electroconductive sheet all at once by e.g. a multilayercoextrusion method employing a feed block or a multimanifold die.

The method for bringing the surface roughness Ra to be from 0.6 to 4.0μm is not particularly limited, but a method of incorporating aninorganic filler such as talc, calcium carbonate, mica or isinglass intothe resin, a method of incorporating natural rubber or synthetic rubber,or a method of embossing the surface by an embossing roll, may bementioned. The method of embossing the surface by an embossing roll hassuch advantages that the dynamic properties and fabrication propertiesof the electroconductive sheet will not be impaired, it can be widelyapplied to e.g. a vinyl chloride resin, a polycarbonate resin, apolystyrene resin or a polyethylene terephthalate resin, which is usedas an electroconductive sheet for a carrier tape at the present time,and further, as a cover material, one which is conventionally used canbe utilized as it is.

The entire thickness of the electroconductive sheet is preferably from0.1 to 3.0 mm, and the thickness of the electroconductive resincomposition layer is preferably from 2 to 80% of the entire thickness.If the entire thickness is less than 0.1 mm, the strength of thepackaging container to be obtained by forming the electroconductivesheet tends to be inadequate, and if it exceeds 3.0 mm, forming such aspressure forming, vacuum forming or thermo-forming tends to bedifficult. Further, if the thickness of the electroconductive resincomposition layer is less than 2%, the surface resistivity of thepackaging container obtained by forming such an electroconductive sheettends to be so high that no adequate antistatic effects can be obtained,and it exceeds 80%, the processability in e.g. pressure-forming,vacuum-forming or thermoforming tends to be poor.

The electroconductive sheet of the present invention is useful as apackaging material for electronic parts such as IC or electronic partsusing IC, and is used for injection-molded trays, vacuum-formed trays,magazines and carrier tapes, and it is particularly suitable for carriertapes.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention will be explained in further detail withreference to Examples. However, it should be understood that the presentinvention is by no means restricted to such specific Examples.

EXAMPLE 1

As an electroconductive resin composition, an electroconductive resincompound was obtained by preliminarily kneading a polycarbonate typeresin (Panlight L-1225, manufactured by Teijin Chemicals Ltd.) and 12 wt% of KETJENBLACK EC (manufactured by LION-AKZO) based on thepolycarbonate type resin, by means of a φ50 mm vented twin-screwextruder, followed by pelletizing. The electroconductive resin compoundwas laminated on each side of an acrylonitrile-butadiene-styrenecopolymer type resin (Techno ABS YT-346, manufactured by Techno PolymerCo., Ltd.) as a thermoplastic resin for a substrate layer of anelectroconductive sheet, by a feed block method using a φ65 mm extruder(L/D=28), a φ40 mm extruder (L/D=26) and a T-die having a width of 500mm to obtain a three-layer electroconductive sheet having an entirethickness of 300 μm and a thickness of the electroconductive resincomposition layer of 30 μm on each side.

EXAMPLE 2

As an electroconductive resin composition, an electroconductive resincompound was obtained by preliminarily kneading a polycarbonate typeresin (Panlight L-1225, manufactured by Teijin Chemicals Ltd.) and 20 wt% of Denka Black granules (manufactured by Denki Kagaku Kogyo K.K.)based on the polycarbonate type resin, by a φ50 mm vented twin-screwextruder, followed by pelletizing. The above electroconductive resincompound was laminated on each side of a mixture comprising anacrylonitrile-butadiene-styrene copolymer type resin (Techno ABS YT-346,manufactured by Techno Polymer Co., Ltd.) and 5 wt % of a polycarbonatetype resin (Panlight L-1225, manufactured by Teijin Chemicals Ltd.)added thereto, as a thermoplastic resin for a substrate layer of anelectroconductive sheet, in the same manner as in Example 1 to obtain athree-layer electroconductive sheet having an entire thickness of 200 μmand a thickness of the electroconductive resin composition layer of 20μm on each side.

EXAMPLE 3

An electroconductive resin compound was obtained in the same manner asin Example 1. The electroconductive resin compound was laminated on eachside of a resin comprising an acrylonitrile-butadiene-styrene copolymertype resin (Techno ABS YT-346, manufactured by Techno Polymer Co., Ltd.)and 10 wt % of said electroconductive resin compound added thereto, as aresin for a substrate layer of an electroconductive sheet, by using aφ65 mm extruder (L/D=28), two φ40 mm extruders (L/D=26) and amultimanifold die for three layers of three types, having a width of 650mm to obtain a three-layer electroconductive sheet having an entirethickness of 500 μm and a thickness of the electroconductive resincomposition layer of 40 μm on each side.

EXAMPLE 4

A three-layer electroconductive sheet was obtained in the same manner asin Example 3 except that a polystyrene type resin (Toyo Styrol E640N,manufactured by Toyo Styrene) was used as the resin for a substratelayer of an electroconductive sheet.

COMPARATIVE EXAMPLE 1

A three-layer electroconductive sheet was obtained in the same manner asin Example 1 except that an electroconductive resin compound obtained bypreliminarily kneading 78 wt % of a polystyrene type resin (Toyo StyrolE640N, manufactured by Toyo Styrene), 10 wt % of a HDPE resin (Hyzex5000H, manufactured by Mitsui Chemicals, Inc.) and 12 wt % ofKETJENBLACK EC (manufactured by LION-AKZO) by a φ50 mm vented twin-screwextruder, followed by pelletizing, was used as the electroconductiveresin composition.

COMPARATIVE EXAMPLE 2

A three-layer electroconductive sheet was obtained in the same manner asin Example 1 except that an electroconductive resin compound obtained bypreliminarily kneading a polystyrene type resin (Toyo Styrol E640N,manufactured by Toyo Styrene) and 12 wt % of KETJENBLACK EC(manufactured by LION-AKZO) by a φ50 mm vented twin-screw extruder,followed by pelletizing, was used as the electroconductive resincomposition and a polystyrene type resin (Toyo Styrol E640N,manufactured by Toyo Styrene) was used as the resin for a substratelayer of an electroconductive sheet.

The electroconductive sheets thus prepared were evaluated. The resultsare shown in Table 1.

TABLE 1 Tensile properties (flow direction/width direction) StrengthSurface Breaking Strength at yield Tensile Falling resistivity extensionat break point modulus off of (Ω) (%) (MPa) (MPa) (MPa) carbon Ex. 1 10⁴12/11 42/41 48/49 1760/1718 ⊚ Ex. 2 10⁴ 10/9  45/43 52/50 1852/1769 ⊚Ex. 3 10⁴ 12/12 43/43 50/50 1812/1750 ⊚ Ex. 4 10⁴ 8/9 40/40 46/451720/1680 ⊚ Comp. 10⁴ 99/23 32/20 39/38 1469/1453 ◯ Ex. 1 Comp. 10⁴96/75 25/20 25/23 1666/1539 X Ex. 2

EXAMPLE 5

A three-layer electroconductive sheet was obtained in the same manner asin Example 1 except that embossing was applied on the surface of oneside of the electroconductive sheet by means of a metal embossing rollhaving a surface roughness Ra of 3.2 μm.

EXAMPLE 6

A three-layer electroconductive sheet was obtained in the same manner asin Example 2 except that embossing was applied on the surface of oneside of the electroconductive sheet by means of a metal embossing rollhaving a surface roughness Ra of 0.9 μm.

EXAMPLE 7

A three-layer electroconductive sheet was obtained in the same manner asin Example 3 except that embossing was applied on the surface of oneside of the electroconductive sheet by means of a silicone rubber rollcontaining sand.

EXAMPLE 8

A three-layer electroconductive sheet was obtained in the same manner asin Example 4 except that embossing was applied on the surface of oneside of the electroconductive sheet by means of a metal embossing rollhaving a surface roughness Ra of 1.9 μm.

COMPARATIVE EXAMPLE 3

A three-layer electroconductive sheet was obtained in the same manner asin Comparative Example 1, except that embossing was applied on thesurface of each side of the electroconductive sheet by means of a metalembossing roll having a surface roughness Ra of 0.3 μm, so that theelectroconductive sheet had high gloss on the surface of each side.

COMPARATIVE EXAMPLE 4

A three-layer electroconductive sheet was obtained in the same manner asin Comparative Example 2 except that embossing was applied on thesurface of one side of the electroconductive sheet by means of a metalembossing roll having a surface roughness Ra of 6.7 μm. However, thesurface of the electroconductive sheet had intense irregularities, andthe appearance of the sheet was very poor.

The above electroconductive sheets thus prepared were evaluated. Theresults are shown in Table 2.

TABLE 2 Tensile properties (flow direction/width direction) StrengthSurface Breaking Strength at yield Tensile Falling Surface Imageresistivity extension at break point modulus off of roughness Surfaceinspection (Ω) (%) (MPa) (MPa) (MPa) carbon (μm) gloss propriety Ex. 510⁴ 12/11 42/41 48/49 1760/1718 ⊚ 3.76 2 ◯ Ex. 6 10⁴ 10/9  45/43 52/501852/1769 ⊚ 0.67 21 ◯ Ex. 7 10⁴ 12/12 43/43 50/50 1812/1750 ⊚ 1.09 17 ◯Ex. 8 10⁴ 8/9 40/40 46/45 1720/1680 ⊚ 2.11 5 ◯ Comp. 10⁴ 99/23 32/2039/38 1469/1453 ◯ 0.22 65 X Ex. 3 Comp. 10⁴ 96/75 25/20 25/23 1666/1539X 4.55 1 ◯ Ex. 4

EXAMPLE 9

A polycarbonate type resin (Panlight L-1225, manufactured by TeijinChemicals Ltd.), and 12 wt % of carbon black (KETJENBLACK EC,manufactured by LION-AKZO) and 5 wt % of a graft resin (Modiper A-4400,manufactured by NOF Corporation, main chain: 70 wt %/side chain: 30 wt%), based on the polycarbonate type resin, were preliminarily kneaded bymeans of a φ50 mm vented twin-screw extruder, followed by pelletizing,to obtain a resin composition.

Said resin composition was sheeted by means of a φ65 mm extruder(L/D=28) and a T-die having a width of 500 mm to obtain anelectroconductive sheet having an entire thickness of 300 μm.

EXAMPLE 10

A polycarbonate type resin (Panlight L-1225, manufactured by TeijinChemicals Ltd.) and 12 wt % of carbon black (KETJENBLACK EC,manufactured by LION-AKZO) based on the polycarbonate type resin, werepreliminarily kneaded by means of a φ50 mm vented twin-screw extruder,followed by pelletizing, to obtain a resin composition.

Said resin composition was sheeted by means of a φ65 mm extruder(L/D=28) and a T-die having a width of 500 mm to obtain anelectroconductive sheet having an entire thickness of 300 μm.

EXAMPLE 11

Using the same resin composition as in Example 9 as a surface layer, andan acrylonitrile-butadiene-styrene copolymer type resin (Techno ABSYT-346, manufactured by Techno Polymer Co., Ltd.) as a resin for asubstrate layer, the surface layer was laminated on each side of thesubstrate layer by means of a feed block method using a φ65 mm extruder(L/D=28), a φ40 mm extruder (L/D=26) and a T-die having a width of 500mm to obtain a three-layer electroconductive sheet having an entirethickness of 300 μm and a thickness of the resin composition layer of 30μm on each side.

EXAMPLE 12

A polycarbonate type resin (Panlight L-1225, manufactured by TeijinChemicals Ltd.), and 20 wt % of acetylene black (Denka Black granules,manufactured by Denki Kagaku Kogyo K.K.) as carbon black and 10 wt % ofa graft resin (Modiper A-4400, manufactured by NOF Corporation), basedon the polycarbonate type resin, were preliminarily kneaded by a φ50 mmvented twin-screw extruder, followed by pelletizing, to obtain a resincomposition. The above resin composition was laminated on each side of amixture comprising an acrylonitrile-butadiene-styrene copolymer typeresin (Techno ABS YT-346, manufactured by Techno Polymer Co., Ltd.) and5 wt % of a polycarbonate type resin (Panlight L-1225, manufactured byTeijin Chemicals Ltd.) added thereto, as a resin for a substrate layer,by means of a φ65 mm extruder (L/D=28), two φ40 mm extruders (L/D=26)and a multimanifold die for three layers of three types having a widthof 650 mm, to obtain a three-layer electroconductive sheet having anentire thickness of 500 μm and a thickness of the surface layer of theresin composition of 40 μm on each side.

The above electroconductive sheets thus prepared were evaluated. Theresults are shown in Table 3.

TABLE 3 Tensile properties Fall- Sur- (flow direction/width direction)ing face Break- Strength Dupont off resis- ing ex- Strength at yieldTensile impact of tivity tension at break point modulus strength car-(Ω) (%) (MPa) (MPa) (MPa) (J) bon Ex. 9 10⁴ 8/7 52/50 52/50 2035/20870.95 ⊚ Ex. 10 10⁴ 10/12 54/53 59/58 2200/2295 0.75 ⊚ Ex. 11 10⁴ 11/1041/39 47/48 1710/1680 0.65 ⊚ Ex. 12 10⁴ 9/8 44/42 50/48 1780/1730 0.68 ⊚

Examples 9 and 10 are different from the viewpoint that a graft resinwas used in Example 9, and it is evident that the Dupont impact strengthincreased by incorporation of the graft resin. Further, as evident fromExamples 11 and 12, not only a monolayer electroconductive sheet butalso a multilayer electroconductive sheet can be prepared by using theresin composition of the present invention.

EXAMPLE 13

As a material for a substrate layer, one obtained by blending apolyethylene terephthalate type resin (PET9921, manufactured by Eastman,IV value: 0.80) and a polycarbonate type resin (Panlight L-1250L,manufactured by Teijin Chemicals Ltd.) in a ratio as identified in Table4, followed by stirring for mixing, was used. As a material for asurface layer, a resin comprising 100 parts by weight of a polycarbonatetype resin (Panlight L-1225L, manufactured by Teijin Chemicals Ltd.) and20 parts by weight of carbon black (Denka Black granules, manufacturedby Denki Kagaku Kogyo K.K.) dispersed therein, was used. Each materialwas dried by a dehumidifier. Then, the material for a surface layer andthe material for a substrate layer were simultaneously extruded by a 40mm single-screw extruder and by a 65 mm single-screw extruder,respectively, at an extrusion temperature of from 260 to 300° C., andthe respective molten resins were laminated by means of a feed block forthree layers of two types (thickness slit ratio=1:8:1), extruded by aT-die having a width of 650 mm, and sheeted by a quenching roll toprepare a three-layer electroconductive sheet having a thickness of 0.30mm and a thickness ratio of 1:8:1 (surface layer:substrate layer:surfacelayer).

EXAMPLES 14 AND 15 AND COMPARATIVE EXMAPLES 5 TO 7

A three-layer electroconductive sheet was prepared in the same manner asin Example 13 except that the composition was as identified in Table 4.

COMPARATIVE EXMAPLES 8

Using the same electroconductive resin for a surface layer as in Example13, the resin was extruded by a φ65 mm single-screw extruder at anextrusion temperature of from 260 to 300° C. to prepare a monolayerelectroconductive sheet.

EXAMPLES 16 AND 17 AND COMPARATIVE EXMAPLES 9 AND 10

A three-layer electroconductive sheet was prepared in the same manner asin Example 14 except that the thickness ratio of the sheet as identifiedin Table 4.

With respect to the electroconductive sheets obtained in Examples andComparative Examples, the surface resistivity, the tensile properties,falling off of carbon, folding strength and impact strength wereevaluated. Further, the electroconductive sheets of Examples andComparative Examples were shaped into a carrier tape by a carrier tapeshaping machine to evaluate secondary processability. The results areshown in Table 5.

TABLE 4 Examples Comparative Examples 13 14 15 16 17 5 6 7 8 9 10Substrate layer PC type resin 60 40 20 40 40  0 100 80 — 40 40 PET typeresin 40 60 80 60 60 100  0 20 — 60 60 Surface layer PC type resin 100 100  100  100  100  100 100 100  100 100  100  Thickness ratio ofsurface layer/substrate 1/8/1 1/8/1 1/8/1 1/18/1 1/6/1 1/8/1 1/8/1 1/8/1— 3/1/3 1/100/1 layer/surface layer

TABLE 5 Examples Comparative Examples 13 14 15 16 17 5 6 7 8 9 10Surface resistivity Ω 2.4 × 3.1 × 1.9 × 3.2 × 2.3 × 2.8 × 3.1 × 4.1 ×1.9 × 2.3 × 5.2 × 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10¹² TensileBreaking extension % 118 136 195 156 89 301 71 75 13 28 169 propertiesStrength at yield point MPa 49 47 46 47 47 46 53 51 59 48 47 Strength atbreak MPa 62 55 49 55 55 47 60 56 55 56 54 Tensile modulus MPa 1566 16281629 1635 1631 1530 1520 1732 1641 1655 1590 Falling off of carbon — ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Folding strength Times 251 384 1083 415 350 3020 21 3815 27 430 Impact strength J 0.7 0.6 0.5 0.7 0.6 1.1 0.5 0.8 0.9 0.8 0.6Secondary processability — ◯ ◯ ◯ ◯ ◯ X Δ ◯ X Δ ◯

EXAMPLE 18

A polycarbonate type resin (Panlight L-1225, manufactured by TeijinChemicals Ltd.) and 12 wt % of carbon black (KETJENBLACK EC,manufactured by LION-AKZO) based on the polycarbonate type resin werepreliminarily kneaded by a φ50 mm vented twin-screw extruder, followedby pelletizing, to obtain an electroconductive resin compound. Theelectroconductive resin compound was laminated on each side of animidated copolymer (Denka Malecca K-400, manufactured by Denki KagakuKogyo K.K.) as a resin for a substrate layer, by means of a feed blockmethod using a φ65 mm extruder (L/D=28), a φ40 mm extruder (L/D=26) anda T-die having a width of 500 mm, to obtain a three-layerelectroconductive sheet having an entire thickness of 300 μm and athickness of the surface layer of 30 μm on each side.

EXAMPLE 19

A polycarbonate type resin (Panlight L-1225, manufactured by TeijinChemicals Ltd.) and 20 wt % of carbon black (Denka Black granules,manufactured by Denki Kagaku Kogyo K.K.) based on the polycarbonate typeresin were preliminarily kneaded by a φ50 mm vented twin-screw extruder,followed by pelletizing, to obtain an electroconductive resin compound.Using an imidated copolymer (Denka Malecca K-510, manufactured by DenkiKagaku Kogyo K.K.) as a resin for a substrate layer, a three-layerelectroconductive sheet having an entire thickness of 200 μm and athickness of the surface layer of 20 μm on each side was prepared in thesame manner as in Example 18.

EXAMPLE 20

An electroconductive compound was obtained in the same manner as inExample 18. The electroconductive compound was laminated on each side ofa resin comprising an imidated copolymer (Denka Malecca K-400,manufactured by Denki Kagaku Kogyo K.K.) and 10 wt % of the aboveelectroconductive compound added thereto, as a resin for a substratelayer, by using of a φ65 mm extruder (L/D=28), two φ40 mm extruders(L/D=26) and a multimanifold die for three layers of three types havinga width of 650 mm, to obtain a three-layer electroconductive sheethaving an entire thickness of 500 μm and a thickness of the surfacelayer of 40 μm on each side.

EXAMPLE 21

A three-layer electroconductive sheet was obtained in the same manner asin Example 18 except that an imidated copolymer (Denka Malecca K-610,manufactured by Denki Kagaku Kogyo K.K.) was used as the resin for asubstrate layer.

COMPARATIVE EXAMPLE 11

A three-layer electroconductive sheet was obtained in the same manner asin Example 18 except that an electroconductive resin compound obtainedby preliminarily kneading a polystyrene resin (Toyo Styrol E640N,manufactured by Toyo Styrene), and 10 wt % of a polyethylene resin(Hyzex 5000H, manufactured by Mitsui Chemicals, Inc.) and 12 wt % ofcarbon black (KETJENBLACK EC, manufactured by LION-AKZO), based on thepolystyrene resin, by a φ50 mm vented twin-screw extruder, followed bypelletizing, was used as the electroconductive resin composition, and anacrylonitrile-butadiene-styrene copolymer type resin (Techno ABS YT-346,manufactured by Techno Polymer Co., Ltd.) was used as the resin for asubstrate layer.

COMPARATIVE EXAMPLE 12

A three-layer electroconductive sheet was obtained in the same manner asin Example 18 except that an electroconductive resin compound obtainedby preliminarily kneading a polystyrene resin (Toyo Styrol E640N,manufactured by Toyo Styrene) and 12 wt % of carbon black (KETJENBLACKEC, manufactured by LION-AKZO) based on the polystyrene resin, by a φ50mm vented twin-screw extruder, followed by pelletizing, was used as theelectroconductive resin composition, and a polystyrene resin (ToyoStyrol E640N, manufactured by Toyo Styrene) was used as the resin for asubstrate layer.

The above electroconductive sheets thus prepared were subjected to thefollowing evaluations.

TABLE 6 Tensile properties (flow direction/width direction) StrengthSurface Breaking Strength at yield Tensile Falling resistivity extensionat break point modulus off of (Ω) (%) (MPa) (MPa) (MPa) carbon Ex. 1810⁴ 28/16 46/43 50/47 1903/1931 ⊚ Ex. 19 10⁴ 22/14 41/40 43/42 1755/1647⊚ Ex. 20 10⁴ 12/12 49/44 52/50 1951/1980 ⊚ Ex. 21 10⁴ 17/11 42/38 44/421756/1620 ⊚ Comp. 10⁴ 99/52 35/32 43/42 1536/1463 ◯ Ex. 11 Comp. 10⁴95/89 21/20 20/19 1166/1139 X Ex. 12

The evaluation methods were as follows.

The physical properties were measured at 23° C. under a humidity of 50%unless otherwise specified. With respect to the folding strength and theimpact strength, the evaluation results were in accordance withstandards as an electroconductive sheet, which is commoner than a moldedproduct.

Surface Resistivity

Using a Rolestar MCP tester manufactured by Mitsubishi PetrochemicalCo., Ltd, the distance between terminals was set to be 10 mm, and theresistivity of the electroconductive sheet was measured at ten points ateven intervals in a width direction in two lines on each side, i.e. at40 points in total, whereupon the logarithmic mean value was taken asthe surface resistivity.

Tensile Properties

In accordance with JIS-K-7127, tensile test was carried out by means ofan Instron type tensile tester at a tension speed of 10 mm/min using aNo. 4 test specimen, and the average of measured values in a flowdirection and in a width direction was taken as the evaluation result.

Dupont Impact Strength

Using a Dupont impact tester (manufactured by TOYO SEIKI SEISAKU-SHO,LTD.), a bullet was made to fall on the electroconductive sheet toobtain a height at 50% break, and the energy value was calculated fromthe weight of the bullet at said height. The calculation was carried outin accordance with JIS-K-7211.

Evaluation of Falling Off of Carbon

The electroconductive sheet in a film form was formed into a carriertape having a pocket with a size of 19 mm×25 mm, which was fixed on ashaking table. IC of QFP 14 mm×20 mm-64 pin was mounted in the pocketportion and vibrated at a speed of 480 reciprocations per minute with astroke of 30 mm in a plane direction for 800,000 times, whereupon thepresence or absence of depositions on the lead portion of IC wasevaluated. The evaluation standards were ⊚: substantially no depositionobserved, ◯: some depositions observed, and X: many depositionsobserved.

Surface Roughness

The centerline surface roughness was measured by means of Surfcom 120Amanufactured by TOKYO SEIMITSU CO., Ltd, in accordance with JIS-B-0651.

Surface Gloss

The gloss of the electroconductive sheet was measured at 5 points oneach side by means of a gloss checker IG-301 manufactured by Horiba,Ltd. to obtain the average value on each side, and the lower value wastaken as the gloss.

Image Inspection Propriety Test

The electroconductive sheet in a film form was formed into a carriertape having a pocket with a size of 19 mm×25 mm. IC of QFP 14 mm×20mm-100 pin was mounted in the pocket portion, whereupon the presence orabsence of virtual image at the bottom of the pocket was confirmed by aCCD camera of 360,000 pixel. The evaluation standards were X: virtualimage clearly confirmed, Δ: virtual image unclearly confirmed, and ◯: novirtual image confirmed.

Folding Strength

In accordance with JIS-P-8116, sampling was carried out in a flowdirection of the electroconductive sheet, and evaluation was carried outwith a load of 500 g with a folding speed of 175 reciprocations perminute.

Secondary Processability

A carrier tape having a width of 24 mm was prepared from theelectroconductive sheet by means of a carrier tape shaping machine(manufactured by EDG) to evaluate processability. The evaluationstandards were ◯: good, Δ: somewhat poor, and X: poor.

INDUSTRIAL APPLICABILITY

According to the present invention, an electroconductive sheet forpackaging an electronic part, which substantially reduces staining ofthe electronic part due to abrasion of the electroconductive sheet withthe electronic part, and which has adequate mechanical strength toendure packaging and mounting of an electronic part at a high speed, anda packaging container for an electronic part, are provided.

What is claimed is:
 1. An electroconductive sheet, comprising: i) asubstrate layer of a thermoplastic resin comprising at least one of anacrylonitrile-butadiene-styrene copolymer resin and a polystyrene resin;ii) and having laminated on at least one side of said substrate layer, asurface layer of an electroconductive resin composition comprising apolycarbonate resin, an acrylonitrile-butadiene-styrene copolymer resin,and from 5 to 50 wt % of carbon black.
 2. An electroconductive sheetcomprising: i) a substrate layer of a thermoplastic resin comprising atleast one of an acrylonitrile-butadiene-styrene copolymer resin and apolystyrene resin; ii) and having laminated on at least one side of saidsubstrate layer, a surface layer of an electroconductive resincomposition comprising a polycarbonate resin, a polybutyleneterephthalate resin, and from 5 to 50 wt % of carbon black, based on thetotal amount of resin.
 3. The electroconductive sheet as claimed inclaim 1, wherein said substrate layer further comprises from 1 to 50 wt% of a polycarbonate resin, based on the thermoplastic resin.
 4. Theelectroconductive sheet as claimed in claim 2, wherein said substratelayer further comprises from 1 to 50 wt % of a polycarbonate resin,based on the thermoplastic resin.
 5. The electroconductive sheet asclaimed in claim 1, wherein said substrate layer further comprises from0.1 to 10 wt % of carbon black, based on the total amount of resin. 6.The electroconductive sheet as claimed in claim 1, wherein said surfacelayer has a surface roughness from 0.6 μm to 4.0 μm.
 7. Theelectroconductive sheet as claimed in claim 1, having a surfaceresisitivity of from 10² to 10¹⁰ Ω on the side of said substrate layeron which said surface layer is laminated.
 8. The electroconductive sheetas claimed in claim 1, which is produced by coextrusion.
 9. Anelectroconductive sheet for packaging an electronic part, comprising theelectroconductive sheet as claimed in claim
 1. 10. A packaging containerfor an electronic part, comprising the electroconductive sheet forpackaging an electronic part as claimed in claim
 9. 11. A carrier tapecomprising the electroconductive sheet for packaging an electronic partas claimed in claim
 9. 12. An electroconductive sheet comprising asubstrate layer of a thermoplastic resin comprising anacrylonitrile-butadiene-styrene copolymer resin and/or a polystyreneresin and having laminated on at least one side of the substrate layer,a surface layer of an electroconductive resin composition comprising apolycarbonate resin, a further resin component, and from 5 to 50 wt % ofcarbon black.
 13. The electroconductive sheet according to claim 12,wherein the substrate layer further contains from 1 to 50 wt % of apolycarbonate resin based on the thermoplastic resin.
 14. Theelectroconductive sheet according to claim 12, wherein the further resincomponent is an acrylonitrile-butadiene-styrene copolymer resin or apolybutylene terephthalate resin.
 15. The electroconductive sheetaccording to claim 13, wherein the further resin component is anacrylonitrile-butadiene-styrene copolymer resin or a polybutyleneterephthalate resin.
 16. The electroconductive sheet as claimed in claim1, wherein said substrate layer further comprises an ethylene-ethylacrylate resin or an ethylene-vinyl acetate copolymer resin, as amodifier.
 17. A packaging container for an electronic part, comprisingthe electroconductive sheet of claim
 16. 18. A carrier tape comprisingthe electroconductive sheet of claim
 16. 19. The electroconductive sheetas claimed in claim 2, wherein said substrate layer further comprises anethylene-ethyl acrylate resin or an ethylene-vinyl acetate copolymerresin, as a modifier.
 20. A packaging container for an electronic part,comprising the electroconductive sheet of claim
 19. 21. A carrier tapecomprising the electroconductive sheet of claim
 19. 22. Theelectroconductive sheet according to claim 12, wherein said substratelayer further comprises an ethylene-ethyl acrylate resin or anethylene-vinyl acetate copolymer resin.
 23. A packaging container for anelectronic part, comprising the electroconductive sheet of claim
 22. 24.A carrier tape comprising the electroconductive sheet of claim 22.